FR products are desirable in a wide variety of applications. Products for both private occupancy such as homes and public occupancy such as health care facilities, convalescent care homes, college dormitories, residence halls, hotels, motels and correctional institutions are sometimes governed by regulations which require components having certain FR characteristics for the materials used to construct such products. This is particularly true when bedding and upholstered products are concerned. Components having certain FR characteristics are also needed in a wide array of other applications where fire safety is a concern, including, but not limited to apparel, fire safety gear, vehicle and aircraft seating and walls, as insulators for appliances, walls and duct work and as barriers to separate sensitive controls from heat sources. Generally speaking, a FR product minimizes the amount and rate of heat released from the product upon contact with fire or other source of ignition. The rate of heat released is an indication of the intensity of the fire generated from the FR product as well as how quickly the fire spreads. Slowing the spread of fire advantageously increases the amount of response time for a person in dangerous proximity to the fire to move to a place of safety and a fire department or other public or private safety agency to successfully extinguish the fire.
In the bedding, upholstery and other industries, foams and nonwoven fibers are often used as components of mattresses, sofas, chairs, and seat cushions, backs and arms. Traditionally, urethane foam has been combined with other types of cushioning materials such as cotton batting, latex rubber, and various nonwoven fibers in order to impart desirable comfort, loft and durability characteristics to a finished product. Of these, however, urethane foam is extremely flammable and must be chemically treated or coated to impart FR properties thereto. As it is relatively fire resistant, neoprene foam is often used in bedding and upholstery products as well. However, as both neoprene foam and urethane foam which has been treated to enhance the FR properties thereof are relatively expensive, cost constraints may limit the applications for which neoprene foam and treated urethane are commercially suitable.
Correctional institutions typically use three types of cushion cores for mattresses. The cushion cores include foam, densified synthetic nonwoven fiber which has a density of about 1.5 pounds per cubic foot or greater, and cotton batting. Left untreated, cotton fibers are extremely flammable and burn rapidly. Cotton can, however, be chemically treated, typically with boric acid, to impart fire resistant properties to the cotton. Correctional institutions with heightened fire safety concerns may require their mattresses to meet certain fire safety standards. In these cases, the cushion cores are comprised of neoprene foam or cotton batting which has been treated with boric acid. However, cotton is extremely moisture absorbent. Thus, mattresses comprised of cotton are difficult to maintain in a hygienic condition. Furthermore, cotton mattresses are relatively heavy.
Synthetic and natural nonwoven fibers also have demonstrated usefulness in the construction of FR mattresses and upholstery. Such fibers are inherently lightweight and therefore easy to ship, store and manipulate during processing. When subjected to open flame, many synthetic fibers, particularly polymer fibers and, more specifically, dry polyester fibers, tend to melt and drip rather than burn. In addition, polymer fibers can be coated for fire resistance. For example, polymer fibers which have been treated for fire resistance are commercially available, for example, the polymer fibers marketed under the trade names Trevira FR, Kelvar and Nomex are generally considered to be non-flammable polymer fibers.
Oxidized polyacrylonitrile (oxidized PAN) fibers provide a relatively high degree of fire resistance at a relatively low cost. However, oxidized PAN fibers are difficult to process into batts for use as a barrier layer or filling, particularly in bedding and upholstery applications. More specifically, oxidized PAN fibers are relatively low in weight and specific gravity, thereby making traditional carding methods used to form batts difficult. In addition, oxidized PAN fibers are so-called “dead” fibers because of their relatively little resilience and loft and general incompressibility. In certain applications, in particular, bedding and upholstery applications, an oxidized PAN fiber batt may be unsuitable where comfort and loft are desired. Oxidized PAN fibers are also black in color and thus may be unsuitable in applications which require a light color beneath a light decorative upholstery or mattress layer.
International Patent Publication No. WO 01/68341 A1, which is hereby incorporated by reference as if reproduced in its entirety, disclosed a fire combustion modified batt which incorporated oxidized PAN as a component thereof. The fire combustion modified batt was formed from a blend of between about 5 percent and about 50 percent by volume of binder fibers, with the remaining amount being a blend of carrier and oxidized PAN fibers. In turn, the relative percent volume of oxidized PAN fibers to carrier fibers in the remaining blend would range anywhere from about 15 percent by volume to about 85 percent by volume. For high loft batts, typically, batts having less than a 2:1 ratio of weight (in ounces per square foot) to thickness (in inches.), it was preferred that the blend would include between about 10 percent and about 15 percent of binder fibers while, for densified batts, typically, batts having a 2:1 or greater ratio of weight (in ounces per square foot) to thickness (in inches), it was preferred that the blend would include between about 15 percent and about 40 percent of binder fibers. It was further preferred that the ratio of oxidized PAN fibers to carrier fibers would be about 50 percent to about 50 percent.
For products requirement additional loft, compressibility, resilience and comfort or a light color beneath decorative upholstery, International Patent Publication No. WO 01/68341 A further disclosed a fire combustion modified batt which, in addition to the web comprised of oxidized PAN and nonwoven fibers, also included an additional web comprising nonwoven fibers which were light in color. A surface of the nonwoven web was then disposed to a surface of the blended oxidized PAN fiber web in a conforming relationship to form a batt which was then heated, compressed and cooled together. Alternatively, it was further disclosed that the oxidized PAN web and the nonwoven web could be heated, compressed and cooled separately and then disposed together to form the batt. It was contemplated that in mattresses and seats having a light colored decorative covering, the batt comprising a first, dark colored, layer comprised of oxidized PAN and nonwoven fibers and a second, light colored, layer comprised of nonwoven fibers would be positioned with the second, light colored, layer proximate the decorative covering to shield it from the first, dark colored, layer comprised of oxidized PAN and nonwoven fibers.